High voltage circuit interrupter



s. l. LINDELL HIGH VOLTAGE CIRCUIT INTERRUPTER 3 Sheets-Sheet 1 FiledJune 11, 1954 livr/Emol@ .grdflazde BY S. l. LINDELL HIGH VOLTAGECIRCUIT INTRRUPTER Dec. 17, 1957 Fviled Julie 11, 1954 3 Sheets-Sheet 2IN VEN TOR. ma l Lzd INVENTOR.

Dec, 17, 1957 s. l. LINDELL HIGH VOLTAGE CIRCUIT INTERRUPTER- Filed June11, 1954 United States Patent O HIGH VOLTAGE CIRCUIT INTERRUPTER SigurdI. Lindell, Chicago, Ill., assignor to S & C Electric Company, Chicago,Ill., a corporation of Delaware Application June 11, 1954, Serial No.436,095

11 Claims. (C1. 200--114) This invention relates, generally, to highvoltage circuit interrupters and it has particular relation to dropoutfuses for use on circuits ranging from 4 kv., 14.4 kv., 23 kv., 34.5 kv.and upwardly to 115 kv. It constitutes au improvement over the inventiondisclosed in copending application Serial No. 367,801, led July 14,1953, and assigned to the assignee of this application, now Patent No.2,745,923, issued May 15, 1956.

The fuse construction disclosed in this copending application isprimarily intended for use on circuits operating at 4 kv. to 14.4 kv.using various makes of fuse links. That fuse construction has suicientinterrupting capacity for many installations. However, it is desirableto increase the interrupting capacity of that fuse construction in orderto clear circuits where the maximum short circuit current is likely toexceed that for which the prior device was designed.

When the circuit to which the fuse is applied is energized at a voltageabove 14.4 kv., the line terminals are correspondingly spaced furtherapart aud the fuse tube for connecting them is accordingly increased inlength. This increase in fuse tube length is not necessarily requiredfor circuit interruption and actually may interfere with optimum currentinterrupting ability under certain operating conditions. Because of thisincrease in fuse tube length, difiiculty may be encountered inwithdrawing and controlling the exible lead attached to the lowerterminal of the fuse link when it blows under predetermined overloadconditions. Under severe short circuit conditions the pressure generatedin the fuse tube may rupture it due to needless length of the arc beyondthe arc length required to withstand the recovery voltage. After circuitinterruption, the required disconnect gap must be provided Vand theproper striking distance must be retained in order to maintain safeoperating conditions.

Tests have demonstrated that maximum interrupting capacity of a givendevice of the character disclosed in the above copending application canbe increased substantially by reducing the arc length to an optimumlength which is less than the length of the fuse tube. When operating atvoltages above 14.4 kv. diiculty may be encountered in interrupting lowfault currents such `as may occur in a fuse connected in the circuit tothe primary winding of a transformer when there is a fault in thecircuit connected to its secondary winding. For such higher voltagecircuits the arcing time is longer than is the case for -circuits oflower voltage.

Accordingly, among the objects of this invention are: To provide in adropout fuse of the type that is latched at the top and pivotallymounted at the bottom and there held by a fuse link against unlatchingmovement for positioning the fuse link, and particularly the portionthat blows, remote from the upper end of the fuse tube; to rapidlymechanically withdraw the llexible lead of a fuse link so positionedthereby reducing the arcing time to a `few cycles yand the arc length inthe fuse tube;

2,816,979 Patented Dec. 17, 1957 ice to employ a rigid conductor or aspring and cable assembly extending into the fuse tube from its upperterminal to position the fuse link remotely therefrom and to initiatethe arc incident to blowing of the fuse link close to the exhaust end ofthe fuse tube and in conjunction therewith to provide for eiiectingrapid separation of the fuse link terminals and positive movement of oneof them out of the exhaust end of the fuse tube in order to achieveetiective interruption of low current arcs; to clamp the 'button head ofa replaceable fuse link by rigid conductor means or a stud at a positionremote from the upper fuse tube terminal; to distribute electrostaticstress originating from the fuse tube terminals and avoid puncturing ofthe fuse tube and external ilashover as the result of subjecting it orthe external air to voltage greater than they are capable ofwithstanding; and to provide improved guide means on the upper lineterminal for directing the upper end of the fuse tube into engagementwith the upper line terminal and `at the same time providing forattachment thereto of a load interrupter tool.

Other objects of this invention will, in part, be obvious and in partappear hereinafter.

This invention is disclosed in the embodiments thereof shown in theaccompanying drawings and it comprises the features of construction,combination of elements and arrangement of parts which will be exempliedin the constructions hereinafter set forth land the scope of theapplication of which will -be indicated in the appended claims.

For a more complete understanding of the nature and scope of thisinvention reference can be had to the following detailed description,taken together with the accompanying drawings, in which:

Figure l is a view, partly in side elevation and partly in sectionshowing a fuse construction of the type illustrated in the applicationabove referred to modified to achieve higher interrupting capacity andfor `application to circuits operating at higher voltages;

Figures 2A and 2B, taken together with the former being placed above thelatter, show a longitudinal crosssectional view of the fuse tube andrelated parts modied in accordance with this invention;

Figure 3 is a bottom plan view of the guide bracket that is employed forinsuring that the fuse tube is swung to the closed position andpermitting the application of a load interrupter tool;

Figures 4A and 4B, taken together with the former positioned above thelatter, show a construction which is a modication of that illustrated inFigures 2A and 2B; and

Figure 5 is a vertical sectional view of the upper portion of a stillfurther modified construction for the fuse tube to adapt it for use withuniversal button head fuse links or high voltage circuits and toincrease its interrupting capacity.

Referring now particularly to Figure 1 of the drawings it will beobserved that the reference character 10 designates a channel base atthe ends of which insulators 11 and 12 are mounted. It will beunderstood that the size and number of the insulators 11 and 12 aredetermined by the voltage of the circuit in which the device hereindisclosed is connected and that their spacing apart also is determinedby the disconnecting gap and the insulation level associated with thecircuit voltage. The insulators 11 and 12 carry upper and lower terminalbrackets 13 and 14 in the form of L-shaped members and they, in turn,carry upper and lower line terminals 15 and 16.

The upper line terminal 15 includes an L-shaped terminal pad providedwith a split bolt connector 20 for 3 attachment to a line conductor.rl`he terminal pad 19 is secured by a bolt 21 to one arm of the upperterminal bracket 13 and also is secured by this bolt to a recoil bar 22.Clamped between the terminal pad 19 and the recoil bar 22 by the bolt 21is one end of a top Contact strip 23. A bolt 24 extending through therecoil bar 22 and the horizontal arm of the bracket 13 holds theassembly in predetermined relation to the insulator 11.

The bolt 21 also extends through one arm 25 of an L-shaped metallicbracket 26 which has a depending vertical arm 27 that carries agenerally U-shaped bracket, shown more clearly in Figure 3 of thedrawings. Here it will be noted that the bottom or central portion 29 ofthe bracket 2S is secured by rivets 30 to the arm 27. Also the bracket2S is arranged with the ends 32 of the arms 31 flared outwardly forreceiving therebetween an upper fuse tube terminal 33 mounted on theupper end of a fuse tube that is shown, generally7 at 34. The outflaredends 32 serve to guide the upper fuse tube ter minal 33 into the closedposition when the fuse tube 34 is swung upwardly from the open circuitposition. The combination of the Lshaped bracket 26 and the U- shapedbracket 23 provides a generally Zshaped conducting member with one endportion or arm 25 rigidly secured to the upper line terminal 15, theintermediate portion or arm 27 extending downwardly along the fuse tube34 and the other end portion or bracket 28 extending outwardly past theupper fuse tube terminal 33. In addition the outflared ends 32 of thearms 31 provide means for receiving one terminal of an auxiliary circuitinterrupter such as disclosed in the copending application Ser. No.412,182, filed February 24, 1954, and assigned to the assignee of thisapplication. As there pointed out the auxiliary circuit interrupter canbe positioned to shunt the upper line terminal l and the upper fuse tubeterminal 33 for the purpose of permitting them to be separated withoutarcing when it is ldesired to open the circuit and swing the fuse tube34 to the open circuit position at a time when load current is llowing.

As pointed out hereinbefore the length of the fuse tube 34 and thespacing of the insulators 11 and 12 depends upon the voltage of thecircuit with which the device is intended to operate. For example, ifthe circuit is to be energized at a voltage of 34.5 kv., the overalllength of the fuse tube 34 and the upper fuse tube terminal 33 is of theorder of 231/2 inches.

As shown more clearly in Figure 2A of the drawings the upper fuse tubeterminal 33 includes a brass ferrule 37 which is secured to the upperend of the fuse tube 34. Formed integrally with the ferrule 37 is an arm38 which carries eye 39 for receiving a prong of a switch stick or apart of the auxiliary circuit interrupter, previously referred to, formanipulating the fuse tube 34. The ferrule 37 has a threaded head 40 onwhich a cap 41 is screwed. The cap 41 has a convex head 42 with whichlatch means, shown generally at 43 in Figure l, cooperates. The latchmeans 43 forms a part of the upper line terminal and includes a U-shapedtop contact 44 the upper end of which is secured by rivets 45 to theforward end of the top contact strip 23. The other end of the contact 44is provided with a conical seat 46 for overlying the contact head 42 onthe cap 41. The conical seat 46 is urged into latching engagement withthe convex head 42 when the fuse tube is swung to the closed positionshown in Figure 1 by a coil compression spring 47 which is positionedbetween the underside of the recoil bar 22 and the upper side of theconical seat 46. A contact stud 43 interconnects the upper end of thecontact 44 with the lower end where the conical seat 46 is located andit extends through a hollow bushing 49 in the recoil bar 22 that is heldin position thereon by a lock nut 50. The details of construction of theupper line terminal 15 are set forth 4 more completely in applicationSer. No. 367,801, now Patent No. 2,745,923, issued May 15, 1956, abovereferred to.

At its lower end the fuse tube 34 is provided with a lower fuse tubeterminal as is shown, generally, at 54. This terminal includes a brassferrule having rearwardly extending arms 56 through which a hinge pin 57projects for rockably mounting a toggle member 53. The toggle member 58has oppositely extending trunnions 59 which are positioned in the lowerends of upwardly opening slots 641 in a hinge casting 61 that is securedby bolts 62 and 63 to a horizontal arm of the lower terminal bracket 14.A split bolt connector 64 extends rearwardly from the hinge casting 61for rcceiving a line conductor. The toggle member 5S has a earn portion65 against which an auxiliary contact 66 bears, backed up by anauxiliary contact spring 67. The latter biases the toggle member 58forwardly so that the trunnions 59 interfit with notches 68 at the lowerends of the forward arms of the hinge casting 61 that define the slots60.

Extending through the trunnions S9 is a shaft 71 on which a flipper 72is rockably mounted. The flipper 72 is biased by a spring 73 to withdrawa flexible lead 74 which forms a part of a replaceable fuse link, showngenerally at "/'5 in Figure 2B of the drawings. The fuse link 75preferably is constructed as disclosed in Mc- Mahon Patent No.2,586,171, issued February 19, 1952. However, it will be understood thatother fuse links can be employed. For a more complete understanding ofthe details of construction of the lower fuse tube terminal 54 and howit cooperates with the hinge casting 16 reference can be had to thecopending application Ser. No. 367,801, iled July 14, 1953, now PatentNo. 2,745,923, issued May 15, 1956, above referred to.

The fuse link 7S includes an upper fuse link terminal 76 which has athreaded stud portion 77. The terminal 76 is connected by a strain wire78 and a helical fusible element 79 to a lower fuse link terminal Si?.An in sulating sleeve 81, preferably constructed as disclosed in theMcMahon patent, is secured to the upper fuse link terminal 76 andextends downwardly over the strain wire 78, helical fusible element 79and the lower fuse link terminal 80. It will be observed that theflexible lead 74 is secured to the lower fuse link terminal Sti and thatit extends downwardly out of the open lower end of the sleeve 81 and outof the open lower end of the fuse tube 34.

As pointed out hereinbefore when the length of the fuse tube 34 is madesufficient for the disconnect distance at any voltage rating from 14.4kv. up, it is undesirable to place the fuse link 75 at the extreme upperend. If this is done, then it is necessary to increase the length of theliexible lead 74 and difficulty is encountered in controlling andwithdrawing such a long length of flexible lead from the fuse tube 34 bythe spring operated flipper 72. The arc length is needlessly increasedwith a corresponding increase in pressure generated when high currentsare interrupted. ln accordance with this invention provision is made forpositioning the fuse link 75 remote from the upper fuse tube terminal 33and nearer the lower open end or exhaust end of the fuse tube 34. Forthis purpose a rigid conductor in the form of a silver plated copper rod83 can be used. For the 34.5 kv. fuse, the conductor 33 has a length of5% inches. The conductor S3 has a flanged head 84 which can be clampedbetween the upper end of the threaded head 4@ and the underside of thccap 41. The lower end of the conductor 33 is provided with a threadedsocket 85 for receiving the threaded stud portion 77 of the upper fuselink terminal 76. This construction then positions the strain wire 73and the helical fusible element 79 much closer to the lower open end ofthe fuse tube 34, thereby requiring a corresponding smaller length oftlexible lead 74 to be expelled from the exhaust end of the fuse tube 34when the fuse link 75 blows and limiting the length of the gasgenerating arc and the resulting pressure when high currents areinterrupted.

It is important to proportion properly the wall thickness of the fusetube 34. As shown in Figure 2B, the fuse tube 34 is made up of acomposite tube with the outer layer 88 being formed of a phenoliccondensation product while the lining 89 is formed of fibre. Thethickness of the outer layer 88 and lining 89 is chosen so that at thevoltage of the circuit for which the particular fuse tube 34 isdesigned, it will be capable of preventing dielectric puncture.

The position of the rigid conductor or rod 83 in the fuse tube 34 isshown by broken lines in Figure 1 of the drawings. It will be noted thatits lower end is well below the eye 39 or any metallic part attached tothe ferrule 37 and energized at the potential thereof. Thus, as long asthe upper fuse tube terminal 33 remains in contact with the energizedupper line terminal after the fuse link 75 has blown and the arc hasbeen extinguished, the lines of electrostatic flux will emanate from thelower end of the rod 83 and the likelihood of restriking of the arc orflashover exterior to the fuse tube 34 will be reduced. The fuse tube 34during this period provides a stationary arcing chamber within which thearc is drawn and extinguished. If the arc is restruck, the same willmore likely occur within the fuse tube 34 where it can be more readilyextinguished.

lWith a view to limiting the arc length and distributing electrostaticstress applied to the lower fuse tube terminal 54 after the fuse link 75blows and before the fuse tube 34 drops to the open circuit position, ametallic dielectric stress distribution shield or terminal extension 90may be located at the lower end of the fuse tube 34. This shield orterminal extension 90 preferably is in the form of a metallic tube andit extends upwardly from the lower open end of the fuse tube 34 so thatit is positioned, as Shown in Figure l of the drawings, well above anymetallic part that is connected to the lower fuse tube terminal 54. Thelower portion 91 extends radially outwardly over the lower end of thefuse tube 34 and there is a turned up end 92 which overlies a reducedportion 93 along the lower edge of the brass ferrule 55. In this mannerthe metallic dielectric stress distribution shield or terminal extension90 is permanently connected to the brass ferrule 55 and thus serves todistribute the electrostatic stress applied there* to during the circuitopening operation in fuses of higher voltage rating.

When the fuse link 75 blows as the result of a predetermined overload orshort circuit, the flipper 72 no longer is restrained by the ilexiblelead 74. It swings downwardly under the influence of the spring 73 and,as described in application Ser. No. 367,801, tiled July 14, 1953, nowPatent No. 2,745,923, issued May 15, 1956, withdraws the llexible lead74 from the exhaust end of the fuse tube 34 and unlocks the togglemechanism associated with the toggle member 58 which permits the fusetube 34 to move downwardly and outwardly away from the latch means 43.Since the fuse link 75 is positioned by the conductor 83 away from theupper end of the fuse tube 34, there is a correspondingly lesser lengthof flexible lead 74 to withdraw than would be the case if it werepositioned at the extreme upper end of the fuse tube 34.

As shown in Figures 4A and 4B the fuse link 75 can be positioned in thefuse tube 34 remote from the upper fuse tube terminal 33 and adjacentthe exhaust or lower end by employing a spring and cable assembly thatis shown, generally, at 96. The spring and cable assembly 96 includes abutton head 97 which can be clamped between the threaded head 40 and theunderside of the cap 4l. A

coil tension spring 98 and a ilexible conductor 99 serve to interconnectthe button head 97 and a threaded iitting 100 into which the studportion 77 of the fuse link 75 is screwed. In this embodiment of theinvention, when the fuse link 75 blows, the flexible lead 74 not only iswithdrawn from the lower open end of the fuse tube 34 but also the upperfuse link terminal 76 is withdrawn upwardly into the fuse tube 34. Thisrapid separation of the fuse link terminals 76 and 80 assists inextinguishing both low current and high current arcs that may be drawntherebetween and there is a minimum of metallic vapor expelled.Otherwise the functioning of the fuse employing the spring and cableassembly 96 is as described for the fuse employing the rigid conductor83. The early and prompt build up of the arc voltage limits and reducesthe direct current component in the fault current. By combining theactions of the spring and cable assembly 96 and of the spring actuatedtlipper 72, these improved results are obtained and low and high currentarcs are effectively drawn and extinguished with a minimum of circuitdisturbance and erosion or damage to the fuse tube 34.

In Figure 5 of the drawings the fuse link 75 is shown with a button head103 which is arranged to bear against a shoulder 104 at the lower end ofa metallic sleeve 105. The sleeve 105 has a radial flange 106 at itsupper end which overlies the threaded head 40. The lower end of themetallic sleeve 105 is threaded as indicated at 107 into the upper endof the libre lining S9. It is desirable to clamp the button head 103against the shoulder 104. For this purpose a metallic plug 108 isinserted into the metallic sleeve 105 and bears against the upper end ofthe button head 103 as shown. The plug 108 has a ilanged head 109 whichoverlies the radial flange 106 and is clamped thereto by the cap 41. Theoperation of the fuse employing the construction shown in Figure 5 isthe same as previously described for the operation of the fuse shown inFigures 1, 2A. and 2B of the drawings. It will be understood that themetallic sleeve 105 serves the same purpose as the rigid conductor S3 inmaking it possible to position the fuse link 75 remote from the upperfuse tube terminal 33 and relatively closer to the lower open end of thefuse tube 34. The lower end of the metallic sleeve 105 extends wellbelow any other metallic part connected to the upper fuse tube terminal33 for limiting the length of the arc drawn in the fuse tube 34 and toprovide a conductor energized at the potential of the upper terminal fordistributing electrostatic stress applied to the intermediate section ofthe fuse tube 34, as described previously, after the fuse link 75 hasblown and the arc is being extinguished.

In the various embodiments of the invention, when a relatively low faultcurrent is interrupted and maximum recovery voltage is encountered as inthe interruption of current flow to the primary winding of a step downtransformer on the occurrence of a secondary fault, after the fuse link75 has blown and the arc has been extinguished and before the lower fuselink terminal 80 has been moved to a position below any energizedmetallic part connected to the low fuse tube terminal 54, the fuse linkterminal 80 acts to distribute the electrostatic stress in the samemanner that this stress is distributed by the shield of terminalextension 90. The reason for this is that the terminal 80 is connectedby the llexible lead 74 to the lower fuse tube terminal 54 and thus isenergized at its potential.

Through the use of this invention it is possible not only to increasesubstantially the interrupting capacity of the dropout fuse constructiondesigned for operation at voltages in the 4 kv. to 14.4 kv. range butalso it is possible to employ this dropout fuse construction on circuitsenergized at higher voltages, such as 23 kv., 34.5 kv. and kv.,particularly when the fuse link 75 is constructed as disclosed in theMcMahon patent, without being limited by the necessity of employing alonger fuse tube to take care of the increased spacing required by thehigher voltage level. The are length is reduced, the arcing time is 7reduced, the pressure incident to the evolution of arc extinguishingmaterial is minimized, and the resulting electrostatic stress is sodistributed as to require that any restriking that may occur will takeplace within the fuse tube 34.

Since certain further changes can be made in the foregoing constructionsand different embodiments of the invention can be made without departingfrom the spirit and scope thereof, it is intended that all matters shownin the accompanying drawings and described hereinbefore shall beinterpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A device for interrupting a high voltage electric power circuit onthe blowing of a replaceable fuse link comprising, in combination, upperand lower line terminal members and means mounting the same in insulatedspaced relation, a fuse tube for receiving the fuse link and having fusetube terminals at its ends for connection to said line terminals, latchmeans on said upper line terminal cooperating with the upper fuse tubeterminal to hold said fuse tube in the closed position, mounting meanson the lower fuse tube terminal pivotally supporting the same on saidlower line terminal and arranged to be restrained by the fuse link aslong as it remains intact to hold said fuse tube in the closed positionand to permit it to move downwardly and away from said latch means onblowing of the fuse link, conductor means connected to said upper fusetube terminal and extending downwardly therefrom into said fuse tube fora distance several times the diameter thereof and below the lowermostpart of said upper fuse tube terminal for detachable connection at itslower end to the upper end of the fuse link to position the portionthereof that is ruptured on blowing remote from the upper end of saidfuse tube and relatively closer to its lower end, and conductor meanspermanently connected to said lower fuse tube terminal and extendingupwardly therefrom into said fuse tube for a distance several times thediameter 'thereof and above the uppermost part of said lower fuse tubeterminal and any metallic part connected thereto for distributingelectrostatic stress after blowing 0f the fuse link and before saidupper fuse tube terminal disengages said upper line terminal.

2. A device for interrupting a high voltage electric power circuit onthe blowing of a replaceable fuse link comprising, in combination, upperand lower line terminal members and means mounting the same in insulatedspaced relation, a fuse tube for receiving the fuse link and having fusetube terminals at its lo\ er ends for connection to said line terminals,latch means on said upper line terminal cooperating with the upper fusetube terminal to hold said fuse tube in the closed position, mountingmeans on the lower fuse tube terminal pivotally supporting the same onsaid lower line terminal including a flipper biased away from the lowerend of said fuse tube and arranged to be restrained by the fuse link aslong as it remains intact to hold said fuse tube in the closed positionand to permit it to move downwardly and away from said latch means onblowing of the fuse link whereupon Said flipper withdraws the remainingportion of the fuse link from said lower end of said fuse tube,conductor means connected to said upper fuse tube terminal and extendingdownwardly therefrom into said fuse tube for a distance several timesthe diameter thereof and below the lowermost part of said upper fusetube terminal for detachable connection at its lower end to the upperend of the fuse link to position the portion thereof that is ruptured onblowing remote from the upper end of said fuse tube and relativelycloser to its lower end, and conductor means permanently connected tosaid lower fuse tube terminal and extending upwardly therefrom into saidfuse tube for a distance several times the diameter thereof and abovethe uppermost part of said lower fuse tube terminal and any metallicpart connected thereto for distributing .electrostatic stress afterblowing of the fuse link 8 and before said upper fuse tube terminaldisengages said upper line terminal.

3. A device for interrupting a high voltage electric power circuit onthe blowing of a replaceable fuse link comprising, in combination, upperand lower line terminal members and means mounting the same in insulatedspaced relation, a fuse tube for receiving the fuse link and having fusetube terminals at its ends for connection to said line terminals, latchmeans on said upper line terminal cooper ting with the upper fuse tubeterminal to hold said fuse tube in the closed position, mounting meanson the lower fuse tube terminal pivotally supporting the same on saidlower line terminal including a flipper biased away from the lower endof said fuse tube and arranged to be restrained by the fuse link as longas it remains intact to hold said fuse tube in the closed position andto permit it to move downwardly and away from said latch means onblowing of the fuse link whereupon said flipper withdraws the remainingportion of the fuse link from said lower end of said fuse tube, arod-lite conductor connected to said upper fuse tube terminal andextending downwardly therefrom into said fuse tube for a distanceseveral times the diameter thereof and below the lowermost part of saidupper fuse tube terminal for etachable connection at its lower end tothe upper end of the fuse link to position the portion thereof that isruptured on blowing remote from the upper end of said fuse tube andrelatively closer to its lower end, and conductor means permanentlyconnected to said lower fuse tube terminal and extending upwardlytherefrom into said fuse tube for a distance several times the diameterthereof and above the uppermost part of said lower fuse tube terminaland any metallic part connected thereto for distributing electrostaticstress after blowing of the fuse link and before said upper fuse tubeterminal disengages said upper line terminal.

4. A device for interrupting a high voltage electric power circuitcomprising, in combination, upper and lower line terminals and meansmounting the same in insulated spaced relation, a fuse tube havingterminals at its ends for connection to said line terminals with itslower end open and its upper end closed by the upper fuse tube terminal,latch means on said upper line terminal cooperating with said upper fusetube terminal to hold said fuse tube in the closed position, mountingmeans on the lower fuse tube terminal pivotally supporting the fuse tubeon said lower line terminal including a flipper biased away from thelower end of said fuse tube and holding said fuse tube in closedposition and arranged to permit it to move downwardly and away from saidlatch means and to swing to open position, conductor means connected tosaid upper' fuse tube terminal and extending downwardly therefrom intosaid fuse tube, a replaceable fuse link having relatively infusibleupper and lower terminals and a flexible lead the upper end of saidlower fuse link terminal being located above the uppermost part of saidlower fuse tube terminal and said llexible lead being connected theretoand extending out of the lower end of said fuse tube, said fuse tubeproviding an arcing chamber stationary relative to said fuse link, andmeans interconnectinfy said flipper and said other end of said flexiblelead whereby the former is restrained by the latter as long as said fuselink remains intact and said flexible lead is withdrawn by said flipperwhen said fuse link blows, said upper fuse link terminal beingdetacbably connected to thc lower end of said conductor means in saidrelatively stationary arcing chamber in such position that the distancebetween its lower end and said lower fuse tube terminal is substantiallyless than the length of the bore of said fuse tube.

5. The invention as set forth in claim 4 wherein the conductor meansconnected to the upper fuse tube terminal is a rod-like conductor.

6. The invention as set forth in claim 4 wherein the conductor meansconnected to the upper fuse tube tcrminal is a spring and cable assemblywhich withdraws the upper fuse link terminal into the fuse tube when thefuse link blows.

7. The invention as set forth in claim 4 wherein the flipper is biasedby a spring individual thereto.

8. A device for interrupting a high voltage electric power circuit onthe blowing of a replaceable fuse link comprising, in combination, upperand lower line terminal members and means mounting the same in insulatedspaced relation, a fuse tube for receiving the fuse link and having fusetube terminals at its ends for connection to said line terminals, latchmeans on said upper line terminal cooperating with the upper fuse tubeterminal to hold said fuse tube in the closed position, mounting meanson the lower fuse tube terminal pivotally supporting the same on saidlower line terminal including a flipper biased away from the lower endof said fuse tube, means for interconnecting said flipper and the fuselink whereby the former is restrained by the latter as long as itremains intact to hold said fuse tube in the closed position and topermit it to move downwardly and away from said latch means on blowingof the fuse link whereupon said ipper withdraws the remaining portion ofthe fuse link from said lower end of said fuse tube, said fuse tubeproviding an arcing chamber stationary relative to said fuse link, and aspring and cable assembly connected to said upper fuse tube terminal andextending downwardly therefrom into said fuse tube for a distanceseveral times the diameter thereof and below the lowermost part of saidupper fuse tube terminal for detachable connection at its lower end tothe upper end of the fuse link in said relatively stationary arcingchamber to position the portion thereof that is ruptured on blowingremote from the upper end of said fuse tube and relatively closer to itslower end and for withdrawing the upper portion of the fuse link intosaid fuse tube when the fuse link blows.

9. The invention as set forth in claim 4 wherein the conductor meansconnected to the upper fuse tube terminal is a metallic sleeve having aradially inwardly extending shoulder at its lower end for receiving thebutton head of a fuse link.

10. The invention as set forth in claim 4 wherein the conductor meansconnected to the upper fuse tube terminal is a metallic sleeve having aradially inwardly extending shoulder at its lower end for receiving thebutton head of a fuse link, and a metallic plug extends into saidmetallic sleeve for bearing against the upper surface of said buttonhead to clamp the same against said shoulder.

11. A high voltage circuit interrupter comprising, in combination, upperand lower line terminal members and means mounting the same in insulatedspaced relation, a fuse tube having fuse tube terminals at its ends forconnection to said line terminals, latch means on said upper lineterminal cooperating with the upper fuse tube terminal to hold said fusetube in the closed position, mounting means on the lower fuse tubeterminal pivotally supporting the same on said lower line terminal andarranged to be restrained by a fuse link to hold said fuse tube in theclosed position and to permit it to move downwardly and away from saidlatch means on blowing of the fuse link, conductor means connected tosaid upper fuse tube terminal and extending downwardly therefrom intosaid fuse tube for a distance several times the diameter thereof andbelow the lowermost part of said upper fuse tube terminal, a replaceablefuse link including upper and lower fuse link terminals interconnectedby fusible means with the upper fuse link terminal connected to thelower end of said conductor means and the lower fuse link terminalconnected by a exible conductor to said lower fuse tube terminal, saidupper and lower fuse link terminals being disposed respectively belowand above any other energized conducting part connected to said upperand lower fuse tube terminals whereby on blowing of said fusible meansand extinction of the arc between said fuse link terminals the resultingelectrostatic stress distribution is such as to require any restrikingof the arc to occur within said fuse tube, and conductor meanspermanently connected to said lower fuse tube terminal and extendingupwardly therefrom into said fuse tube for a distance several times thediameter thereof and above the uppermost part of said lower fuse tubeterminal for distributing electrostatic stress after blowing of saidfuse link and withdrawal of said lower fuse link terminal to a positionbelow the upper end of said conductor means and before said upper fusetube terminal disengages said upper line terminal.

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